Effect of Temperature and Cathodic Disbondment on the Performance of FBE and Hybrid Epoxy Coatings in Sabkha Soil and Persian Gulf Environments

Articles in Press

Document Type : Original Article

Authors

1 institute for color science and technology

2 Institute for color science and technology

Abstract

Fusion-bonded epoxy (FBE) and a commercial hybrid epoxy were evaluated for their barrier performance and damage tolerance in simulated Sabkha soil and Persian Gulf seawater environments at 23°C and 36°C. The study utilized electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), and adhesion testing to quantify coating degradation in intact, scratched, and cathodic disbondment (CD) scenarios. Results indicated a distinct performance trade-off: intact FBE exhibited superior primary barrier properties, maintaining higher low-frequency impedance modulus (>1010 Ω cm²) and lower capacitance compared to the hybrid system, attributing to its tighter microstructure. However, under damaged conditions coupled with cathodic protection, the hybrid epoxy demonstrated superior defect tolerance. While the FBE coating showed increased susceptibility to oxide lift and alkaline-induced delamination, particularly in Persian Gulf seawater at 36°C, the hybrid system effectively resisted interfacial degradation, maintaining a NACE rating of 2 in the same aggressive environment. Mechanical testing confirmed that both systems possessed excellent initial adhesion with pull-off strengths consistently exceeding 1000 psi and cohesive failure modes. The findings suggest that while FBE offers better initial isolation, the hybrid epoxy provides enhanced reliability in scenarios where mechanical damage and subsequent cathodic disbondment are the primary failure risks.

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Progress in Color, Colorants and Coatings

Articles in Press, Accepted Manuscript
Available Online from 09 March 2026

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